# WHATWG HTML Popover Auto/Hint/Stack Transition Plan Calculator

> WHATWG HTML Popover Auto/Hint/Stack Transition Plan Calculator is a paid API for AI agents from detect.halowerk.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-11-04).

Computes normative WHATWG-spec popover state transitions (auto, hint, manual) for a given URL's declared popovers, including demotion and parent cascade rules, as of the bound spec date 26.10.2026.

## Facts

- Endpoint: POST https://detect.halowerk.com/u/html-popover-auto-hint-stack-transition-plan?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-04
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/whatwg-html-popover-auto-hint-stack-transition-plan-calculator-dce8b633
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_lgb8ykaNLXtju5bjMBwkN

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability whatwg-html-popover-auto-hint-stack-transition-plan-calculator-dce8b633 -d '<json body>'
```

Example prompt: Can you compute the normative WHATWG popover transition plan for the page at https://example.com/mypage — specifically how the auto, hint, and manual popovers interact under a source:null show/hide program, including any demotion and parent cascade steps?

## When to prefer this

Use this endpoint when you need to verify or debug WHATWG-normative popover state transitions for a specific HTML page — especially for auto/hint/manual popover interactions, demotion logic, and parent cascade behavior — against the fixed 26.10.2026 spec snapshot. Prefer this over browser DevTools or runtime testing when you need a purely spec-based, deterministic computation independent of actual browser implementation.

## Known failure modes

- URL is unreachable or returns a non-HTML response — computation cannot proceed
- Page contains no declared popovers — empty or trivial transition plan returned
- URL scheme is not http or https — rejected by input schema validation
- Popover declarations are ambiguous or malformed — may produce incomplete transition trace
- Spec edge cases not covered by the bound 26.10.2026 snapshot — undefined behavior not modeled

## How this service works

Berechnet ausschließlich normative WHATWG-Transitionen nach gebundenem Stand26.10.2026 für deklarierte Auto-/Hint-/Manual-Popover unter einem festen source:null-Show-/Hide-Programm; einschließlich Herabstufung und Elternkaskaden. Keine Aussage über tatsächlichen Browserzustand oder Browserkompatibilität.

## Output

A structured normative transition plan listing each state change for declared auto, hint, and manual popovers, including demotion events and parent cascade sequences, computed according to the WHATWG spec bound to 26.10.2026. Does not reflect actual browser behavior or cross-browser compatibility.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "format": "uri",
   "pattern": "^https?://"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/whatwg-html-popover-auto-hint-stack-transition-plan-calculator-dce8b633/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from detect.halowerk.com](https://www.zero.xyz/host/detect.halowerk.com/llms.txt)